Phase 7 & 8: Routes optimization refactor and request utils split

Phase 7 - Optimization handlers:
- Create api/optimization_handlers.py with try_prefix_detection,
  try_quota_mock, try_title_skip, try_suggestion_skip, try_filepath_mock
- Add try_optimizations() that runs handlers in order
- Refactor routes.create_message to use try_optimizations()
- Update test_routes_optimizations patch targets

Phase 8 - Request utils split:
- Create api/detection.py: is_quota_check_request, is_title_generation_request,
  is_prefix_detection_request, is_suggestion_mode_request,
  is_filepath_extraction_request
- Create api/command_utils.py: extract_command_prefix, extract_filepaths_from_command
- Slim request_utils.py to get_token_count + re-exports for backward compat

Co-authored-by: Ali Khokhar <alishahryar2@gmail.com>

api/optimization_handlers.py

@@ -0,0 +1,146 @@
+"""Optimization handlers for fast-path API responses.
+
+Each handler returns a MessagesResponse if the request matches and the
+optimization is enabled, otherwise None.
+"""
+
+import logging
+import uuid
+from typing import Optional
+
+from .models.anthropic import MessagesRequest
+from .models.responses import MessagesResponse, Usage
+from .detection import (
+    is_quota_check_request,
+    is_title_generation_request,
+    is_prefix_detection_request,
+    is_suggestion_mode_request,
+    is_filepath_extraction_request,
+)
+from .command_utils import extract_command_prefix, extract_filepaths_from_command
+from config.settings import Settings
+
+logger = logging.getLogger(__name__)
+
+
+def try_prefix_detection(
+    request_data: MessagesRequest, settings: Settings
+) -> Optional[MessagesResponse]:
+    """Fast prefix detection - return command prefix without API call."""
+    if not settings.fast_prefix_detection:
+        return None
+
+    is_prefix_req, command = is_prefix_detection_request(request_data)
+    if not is_prefix_req:
+        return None
+
+    return MessagesResponse(
+        id=f"msg_{uuid.uuid4()}",
+        model=request_data.model,
+        content=[{"type": "text", "text": extract_command_prefix(command)}],
+        stop_reason="end_turn",
+        usage=Usage(input_tokens=100, output_tokens=5),
+    )
+
+
+def try_quota_mock(
+    request_data: MessagesRequest, settings: Settings
+) -> Optional[MessagesResponse]:
+    """Mock quota probe requests."""
+    if not settings.enable_network_probe_mock:
+        return None
+    if not is_quota_check_request(request_data):
+        return None
+
+    logger.info("Optimization: Intercepted and mocked quota probe")
+    return MessagesResponse(
+        id=f"msg_{uuid.uuid4()}",
+        model=request_data.model,
+        role="assistant",
+        content=[{"type": "text", "text": "Quota check passed."}],
+        stop_reason="end_turn",
+        usage=Usage(input_tokens=10, output_tokens=5),
+    )
+
+
+def try_title_skip(
+    request_data: MessagesRequest, settings: Settings
+) -> Optional[MessagesResponse]:
+    """Skip title generation requests."""
+    if not settings.enable_title_generation_skip:
+        return None
+    if not is_title_generation_request(request_data):
+        return None
+
+    logger.info("Optimization: Skipped title generation request")
+    return MessagesResponse(
+        id=f"msg_{uuid.uuid4()}",
+        model=request_data.model,
+        role="assistant",
+        content=[{"type": "text", "text": "Conversation"}],
+        stop_reason="end_turn",
+        usage=Usage(input_tokens=100, output_tokens=5),
+    )
+
+
+def try_suggestion_skip(
+    request_data: MessagesRequest, settings: Settings
+) -> Optional[MessagesResponse]:
+    """Skip suggestion mode requests."""
+    if not settings.enable_suggestion_mode_skip:
+        return None
+    if not is_suggestion_mode_request(request_data):
+        return None
+
+    logger.info("Optimization: Skipped suggestion mode request")
+    return MessagesResponse(
+        id=f"msg_{uuid.uuid4()}",
+        model=request_data.model,
+        role="assistant",
+        content=[{"type": "text", "text": ""}],
+        stop_reason="end_turn",
+        usage=Usage(input_tokens=100, output_tokens=1),
+    )
+
+
+def try_filepath_mock(
+    request_data: MessagesRequest, settings: Settings
+) -> Optional[MessagesResponse]:
+    """Mock filepath extraction requests."""
+    if not settings.enable_filepath_extraction_mock:
+        return None
+
+    is_fp, cmd, output = is_filepath_extraction_request(request_data)
+    if not is_fp:
+        return None
+
+    filepaths = extract_filepaths_from_command(cmd, output)
+    logger.info("Optimization: Mocked filepath extraction")
+    return MessagesResponse(
+        id=f"msg_{uuid.uuid4()}",
+        model=request_data.model,
+        role="assistant",
+        content=[{"type": "text", "text": filepaths}],
+        stop_reason="end_turn",
+        usage=Usage(input_tokens=100, output_tokens=10),
+    )
+
+
+OPTIMIZATION_HANDLERS = [
+    try_prefix_detection,
+    try_quota_mock,
+    try_title_skip,
+    try_suggestion_skip,
+    try_filepath_mock,
+]
+
+
+def try_optimizations(
+    request_data: MessagesRequest, settings: Settings
+) -> Optional[MessagesResponse]:
+    """Run optimization handlers in order. Returns first match or None."""
+    for handler in OPTIMIZATION_HANDLERS:
+        result = handler(request_data, settings)
+        if result is not None:
+            return result
+    return None